A typical agricultural combine weighs 15,000-20,000 kg. Combines are designed to support headers mounted to the front of the combine, which extend forward as a cantilevered load. Agricultural headers for such combines typically weigh 2000-5000 kg. The header weight, therefore, can be as much as ⅓ the weight of the combine itself. Unlike work vehicles, such as front loaders, headers for combines extend substantially beyond the left and right sides of the combine, having a total width of 10-15 m.
To compensate for the extremely large cantilevered loads applied by the header to the combine, the combine itself is usually provided with two large front drive wheels disposed on either side of the front of the combine, and two much smaller drive wheels disposed on either side of the rear of the combine.
Agricultural combines are typically configured to permit the use of different headers depending upon the type of crop to be harvested. Agricultural combines are equipped with fasteners that permit the different headers to be quickly connected and disconnected from the front of the combine. Headers are not required, however, to operate an agricultural combine. They're only necessary for harvesting crops.
Due to the great weight of the header, the machine dynamics change radically depending on whether the header is installed or removed, and even when a very heavy header is replaced with a very light header (or vice versa). The radical change in total weight and weight distribution will, depending on the configuration, cause the combine to be more prone wheel slippage.
Traction may be controlled in construction vehicles with front loading cantilevered buckets according to one system described in US patent application publication No. US2006/0211535 A1, by using a payload sensor to measure the weight of the payload in the bucket.
In EP 1 488 676 B1, traction may be controlled in a forage combine by changing the spacing between the front and rear wheels based upon the weight of the harvesting header.
In U.S. Pat. No. 7,044,257, it is disclosed that traction may be controlled in an agricultural combine by using wheel speed sensors to measure wheel slippage while the vehicle is being driven through the field, and to change the displacement of hydraulic motors driving those wheels to reduce the relative speed of the slipping wheel.
In US patent application publication US 2005/0217261 A1, traction may be controlled in a working vehicle by monitoring the rotational speeds of the front and rear wheels using speed sensors, calculating the diameter of the wheels, and varying the specific displacement of the hydraulic motors driving those wheels in accordance with rotational speeds.
None of the above examples balances the torque applied by each of the wheels based on the presence or absence of an implement on the vehicle, are on the type of implement on the vehicle. It is an object of this invention to provide such a system.